Barry is on the streets, while Cisco and Wells bicker at S.T.A.R. Labs. Suddenly, there's a fuel truck out of control in Barry's vicinity; he gets in, and the steering wheel is locked so he can't slow it down.
Barry uses his speed to get out of the truck and remove all the lugnuts from teh truck's tires, grinding it to a halt without crashing.
At S.T.A.R., Cisco and Caitlin reveal that Turtle is dead.
Back near the truck, Thawne tells Gideon that he has figured out where The Flash is from, and that it's time to start their plans.
At the lab, Barry decides to go to work at the police department, while Wells is going to work on closing the breaches, since losing Turtle sets back the plans to stop Zoom another way.
In Barry's lab, he's depressed, and guilts Patty about her decision to leave. As Patty leaves, Joe and Iris come to see him. Iris tries to give him Patty advice, but Joe tells her that Francine doesn't have much time left.
Cisco comes to see Wells, saying that closing the breaches won't work. Wells tells him that he needs to find how his powers work. Eventually, Wells gets a burst of inspiration and tells Cisco to meet him in the time vault. When Cisco gets to the lab, he finds Wells dressed as the Reverse-Flash. Fear, Wells says, is the trigger.
But when Cisco vibes, he sees the real Reverse-Flash.
At Mercury Labs, the Reverse-Flash shows up to kidnap Christina McGee. The Flash shows up to stop him, saying that Thawne died. Thawne says that's good to know, and that now that he knows what time period The Flash comes from, he'll kill him soon. Before Barry can respond, Thawne punches him, knocking him down, and takes McGee.
At S.T.A.R., they figure out that Thawne is from a timeline remnant -- this is actually his previous version, before he ever killed Barry's mom. He was protected from his "death" by being in the speed force at the time his timeline was erased.
In another lab, Thawne asks McGee to rig some tachyon hardware for him. He threatens to kill her if she doesn't.
At a hospital, Francine says she wishes she could help Wally and Iris, and that if Iris wants to say anything to her, she has to say it while she can. Iris tells her that her whole life of good memories is tainted by the regret that Francine and Wally weren't in them. She tells her that she forgives her for leaving, then breaks down crying and leaves the room.
In the waiting room, Joe hugs her as she sobs.
At the CSI lab, Barry is trying to help Caitlin find the Jay Garrick of Earth-1, so that they can try to use his cells to restore Earth-2 Jay. Patty comes to see Barry and is confused to see him working with Caitlin. She tells him that she doesn't understand why he's being so distant, and he says he's used to everyone he loves leaving. He tells her he wishes things were different for both of them, but they aren't. She says, "me too," and leaves.
At S.T.A.R., Wells has modified Cisco's goggles with tech that will activate his fear centers and make it easier for him to vibe on command. Cisco reluctantly puts them on, and sees numerous different events throughout time. Wells tells him to concentrate on the Reverse-Flash, and Vibe sees him from the end of last week, arriving in Central City. Wells says to try and picture Thawne with Christina McGee, which Vibe does. He watches Thawne murder her after she's completed his tachyon machine.
At S.T.A.R., Cisco tells the team that after he saw the Reverse-Flash kill McGee, he saw him jump into the tachyon thing and get flung forward. When the team tries to track the tachyons, they fail -- and realize that Cisco is seeing the future. They have about three hours before McGee is killed.
At the Police Department, Joe and Patty start talking about Barry -- she has realized that Barry is The Flash. Joe laughs it off, but Patty tells him he's a terrible liar, and leaves. Iris goes to visit Wally, who's working on his car. She tells him that Francine misses him, but he doesn't want to talk about it. He goes to leave, and she stops him by telling him about Eddie's death, and that he didn't get a chance to say good-bye. She tells him that saying good-bye to Francine will help him find peace.
With only minutes left before McGee's death, the team is frustrated by an absence of tachyon activity. Caitlin comes to ask Barry about Earth-1 Jay Garrick. Barry says there's no Jay Garrick on this earth. Joe comes to warn him that Patty knows he's The Flash, but before they can get too far into it, the tachyons start to build up and Barry has to race to save McGee. He does, and breaks the tachyon device, telling Thawne that he's not going anywhere.
Reverse Flash tells him that he'll find another way home, and takes off with Barry in pursuit. He's quick, and manages to evade Barry for a while, but Barry tackles him and starts beating him at super speed. Joe tries to convince Barry not to kill him, just to bring him into S.T.A.R., and finally Barry relents, punching Thawne out.
Once they have him in the pipeline, Barry wants to go confront him, but the rest of the team convinces him not to. Soon, Barry gets a page and Cisco gets a nosebleed.
At a restaurant, Caitlin asks Jay about his Earth-1 doppelganger. He tells her to meet him at Hoffer Park tomorrow, and he'll show her the explanation. She asks why, and he says she has to see it for herself.
Cisco goes to the pipeline to taunt Thawne, and to ask him how he got his ring in his costume. He tells Thawne that his powers, which were key to catching Thawne, were given to him by Thawne and that Thawne is now sitting in a cell the two of them built together.
Barry joins Patty at the CSI Lab. She confronts him about being The Flash, and tells him that she understands everything she didn't understand before. She tells him that if he's honest with her about being The Flash, she'll stay in town. Barry says he can't do that -- that he isn't The Flash -- and Patty leaves in tears.
Barry, remaining in the shadows, comes to ask Thawne why he hates The Flash. Thawne tells him he wasn't always, that he'd been obsessed with The Flash. He recreated the accident, and became The Flash, but Thawne learned when he started to time travel that he's destined to be Barry's greatest enemy -- and so he embraced that destiny. He threatens Barry some more, and Barry's not impressed. Caitlin calls him to the lab, where Cisco is having a seizure and they can't get it under control.
They briefly get him stable, but then he starts to phase out of reality. Wells decides it's damage to the timeline. Wells figures out a way for Barry to loan Thawne some speed and throw him into the future, so it saves Cisco. Thawne tells Barry that this is the story where Thawne learns about Barry's timeline, about S.T.A.R. Labs and Harrison Wells. This is his origin story, and there's nothing they can do about it except save Cisco.
Barry and Thawne run into the particle accelerator, and once there, Barry hurls Thawne into a wormhole, sending him home. Once that's done, Cisco stabilizes.
At the park the next day, Jay tells Caitlin that he had the same idea about his doppelganger. He shows her a man who looks just like him -- Hunter Zolomon. His mother died in childbirth, and he never got speed, so his DNA was never mutated and won't help them. The only way to help Jay is to stop Zoom.
That night, Wally arrives at the West house and tells Iris that he's going to take her advice and go see his mom. He wants her to come with him, and she says she will, and gets her things.
At S.T.A.R., they reveal to Cisco that they sent Thawne to the future to save him, and Cisco is surprised but thanks Barry.
When Barry and Joe talk about Patty leaving, Joe tells him that he's now understanding -- and Barry has to prepare himself for the reality that -- he's going to have to make sacrifices to be The Flash. He gets a call -- it's Patty, who tells him that she's on the train and there's a man with a gun. He suits up and goes to save her...but its' a ruse, so that she could convince Barry to come and face her. She tells him that everything is OK and they exchange meaningful glances before she leaves town.